• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1365-1381
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• 2023

In this paper, a procedure for evaluating the structural integrity of the PCSG (Printed Circuit Steam Generator) unit block is presented with a simplified FE (finite element) analysis technique by applying the homogenization method. The homogenization method converts an inhomogeneous elastic body into a homogeneous elastic body with same mechanical behaviour. This method is effective when the inhomogeneous elastic body has repetitive microstructures, and thus the method was applied to the sheet assembly among the PCSG unit block components. From the method, the homogenized equivalent elastic constants of the sheet assembly were derived. The validity of the determined material properties was verified by comparing the mechanical behaviour with the reference model. Thermo-mechanical analysis was then performed to evaluate the structural integrity of the PCSG unit block, and it was found that the contact region between the steam header and the sheet assembly is a critical point where large bending stress occurs due to the temperature difference.

• SUVANNABHUMI
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• v.11 no.2
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• pp.125-157
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• 2019

It has been widely argued that Area Studies is in a critical condition especially in Australia, Europe and the US. However, in the Southeast Asian region, most especially Indonesia, we are witnessing the rise of Area Studies programs with the establishment of several such programs both in research institutions and universities. In this paper, I will discuss a few examples of Area Studies research on the emerging diasporic connections in Southeast Asia and reflect on the constitution of ethnic networks as "sites" where transnational identities are forged beyond state boundaries. Indeed, transnational movements of people have occurred and continue to happen due to particular events like wars and political turmoil, as well as for economic reasons. Today, we find many diasporic groups, including minorities, in the border areas of Southeast Asian countries and historically, minorities have been known for their movements in mainland Southeast Asia. If previously, the diasporic connections, especially with the homeland, had been very limited or even non-existent, today such connections have emerged across national boundaries. On top of this, economic and social networkings are equally on the rise both within and at transnational levels. It is, therefore, important to discuss the identity of diasporic groups and transnational networkings in the cases of two border areas in Southeast Asia.

• Annual Conference of KIPS
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• 2022.11a
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• pp.541-543
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• 2022

In recent years, retinal disorders have become a serious health concern. Retinal disorders develop slowly and without obvious signs. To avoid vision deterioration, early detection and treatment are critical. Optical coherence tomography (OCT) is a non-invasive and non-contact medical imaging technique used to acquire informative and high-resolution image of retinal area and underlying layers. Disease signs are difficult to detect because OCT images have many areas which are not related to any disease. In this paper, we present a deep learning-based method to perform multi-label classification on a long-tailed OCT dataset. Our method first extracts the region of interest and then performs the classification task. We achieve 98% accuracy, 92% sensitivity, and 99% specificity on our private OCT dataset. Using the heatmap generated from trained convolutional neural network, our method is more robust and explainable than previous approaches because it focuses on areas that contain disease signs.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.433-440
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• 2023

This study aims to establish safety zones for bunkering operations of hydrogen propulsion ships in coastal areas through risk assessment and evaluate their validity. Using a 350 kW-class ferry operating in Busan Port as the subject of analysis, with quantitative risk assessment based on accident consequence and frequency analysis, along with a social risk assessment considering population density. The results of the risk assessment indicate that all scenarios were within acceptable risk criteria and ALARP region. The most critical accident scenarios involve complete hose rupture during bunkering, resulting in jet flames (Frequency: 2.76E-06, Fatalities: 9.81) and vapor cloud explosions (Frequency: 1.33E-08, Fatalities: 14.24). For the recommended safety zone criteria in the 6% hose cross-sectional area leakage scenario, It could be appropriate criteria considering overall risk level and safety zones criteria for hydrogen vehicle refueling stations. This research contributes to establishing safety zone for bunkering operations of hydrogen propulsion ships through risk assessment and provides valuable technical guidelines.

• Structural Engineering and Mechanics
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• v.88 no.4
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• pp.311-322
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• 2023

Riverine flood is one of the critical natural threats to river-crossing bridges. As floods are the most-occurred natural hazard worldwide, survival probability of bridges due to floods must be assessed in a speedy but precise manner. In this regard, the paper presents a reliability-based approach for a rapid assessment of failure probability of vulnerable bridge components under floods. This robust method is generic in nature and can be applied to both concrete and steel girder bridges. The developed methodology essentially utilizes limit state performance functions, expressed in terms of capacity and flood demand, for probable failure modes of various vulnerable components of bridges. Advanced First Order Reliability Method (AFORM), Monte Carlo Simulation (MCS), and Latin Hypercube Simulation (LHS) techniques are applied for the purpose of reliability assessment and developing flood fragility curves of bridges in which flow velocity and water height are taken as flood intensity measures. Upon validating the proposed method, it is applied to a case study bridge that experiences the flood scenario of a river in Gujarat, India. Research outcome portrays how effectively and efficiently the proposed reliability-based method can be applied for a quick assessment of flood vulnerability of bridges in any flood-prone region of interest.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1117-1124
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• 2023

The security of information, including image content, is an essential part of today's communications technology and is critical to secure transmission. In this paper, a new ROI-based image encryption algorithm is proposed that can quickly encrypt images with a security level suitable for environments that require real-time data transmission for images containing sensitive information such as ID cards. The proposed algorithm is based on one dimensional 5-neighbor cellular automata, which can be implemented in hardware and performed hardware-friendly operations. Various experiments and analyses are performed to verify whether the proposed encryption algorithm is safe from various brute-force attacks.

• Journal of Species Research
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• v.13 no.2
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• pp.111-126
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• 2024

Korean bamboo forests encompass 22,067 hectares and are dominated by Phyllostachys species. These forests serve as vital ecosystems, providing nourishment and habitat for diverse flora, fauna, and microorganisms. Among these inhabitants, various fungal species have been documented worldwide, displaying ecological roles as saprobes, parasites, and symbionts within or outside the bamboo host. However, a comprehensive study of bambusicolous fungi within the Korean bamboo ecosystem remains a critical gap in our knowledge. In this study, we conducted an extensive survey of bamboo materials collected from various bamboo forests and subsequently undertook fungal isolation. Primary identification of bambusicolous fungi was achieved through analysis of the internal transcribed spacer (ITS) region. As a result, we identified seven previously unrecorded bambusicolous fungal species (Fusarium bambusarum, Fusicolla violacea, Macroconia gigas, Neopestalotiopsis camelliae-oleiferae, Neopestalotiopsis iberica, Neopestalotiopsis longiappendiculata, and Thyridium punctulatum). Phylogenetic analysis using protein-coding genes appropriate for each taxon and morphological observation were conducted to ensure accurate identification. This study contributes to our understanding of fungal diversity within bamboo forests in Korea.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.329-342
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• 2024

The exponential increase in nitrate pollution of river water poses an immediate threat to public health and the environment. This contamination is primarily due to various human activities, which include the overuse of nitrogenous fertilizers in agriculture and the discharge of nitrate-rich industrial effluents into rivers. As a result, the accurate prediction and identification of contaminated areas has become a crucial and challenging task for researchers. To solve these problems, this work leads to the prediction of nitrate contamination using machine learning approaches. This paper presents a novel approach known as Grey Wolf Optimizer (GWO) based on the Stacked Ensemble approach for predicting nitrate pollution in the Cauvery Delta region of Tamilnadu, India. The proposed method is evaluated using a Cauvery River dataset from the Tamilnadu Pollution Control Board. The proposed method shows excellent performance, achieving an accuracy of 93.31%, a precision of 93%, a sensitivity of 97.53%, a specificity of 94.28%, an F1-score of 95.23%, and an ROC score of 95%. These impressive results underline the demonstration of the proposed method in accurately predicting nitrate pollution in river water and ultimately help to make informed decisions to tackle these critical environmental problems.

• Advances in nano research
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• v.16 no.1
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• pp.91-109
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• 2024

Carbon nanotubes are drawing wide attention of research communities and several industries due to their versatile capabilities covering mechanical and other multi-physical properties. However, owing to extreme operating conditions of the synthesis process of these nanostructures, they are often imposed with certain inevitable structural deformities such as single vacancy and nanopore defects. These random irregularities limit the intended functionalities of carbon nanotubes severely. In this article, we investigate the mechanical behaviour of double-wall carbon nanotubes (DWCNT) under the influence of arbitrarily distributed single vacancy and nanopore defects in the outer wall, inner wall, and both the walls. Large-scale molecular simulations reveal that the nanopore defects have more detrimental effects on the mechanical behaviour of DWCNTs, while the defects in the inner wall of DWCNTs make the nanostructures more vulnerable to withstand high longitudinal deformation. From a different perspective, to exploit the mechanics of damage for achieving defect-induced shape modulation and region-wise deformation control, we have further explored the localized longitudinal and transverse spatial effects of DWCNT by designing the defects for their regional distribution. The comprehensive numerical results of the present study would lead to the characterization of the critical mechanical properties of DWCNTs under the presence of inevitable intrinsic defects along with the aspect of defect-induced spatial modulation of shapes for prospective applications in a range of nanoelectromechanical systems and devices.

• Journal of Distribution Science
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• v.22 no.6
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• pp.69-81
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• 2024

Purpose: Small airports are social and economic enablers and facilitate businesses and individuals. They contribute significantly to the distribution and logistics of the local produce - be it goods or services, thereby impacting the economy but have limited access to funds and poor management restricts their development. Despite the importance, small airports in small cities struggle financially as they are unable to earn profits and have higher operating costs. In other words, this is a paradoxical situation for small airports wherein, despite losses, the regional or national public authorities still finance such airports under socio-economic obligations. Therefore, this study aims to identify the critical success factors for improving small airports' performance and propose a business model. Research design, data and methodology: Using the qualitative research, interviews with 16 stakeholders from Guwahati, Tirupati, Bhubaneswar and Dehradun airports in india were examined. Results: The analysis reveals strategic planning and low cost, non-passenger services, and development of airport economic region as the main factors contributing towards small airports' success. Additionally, providing logistics to the local businesses and creating niche markets are suggested. Conclusions: Small airports, based on their services and the means of targeting customers, could select the relevant approach to improve their overall performance and improve profitability.