• Ocean Systems Engineering
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• v.13 no.1
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• pp.43-55
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• 2023

In this study, the SCFs in tubular T-joints stiffened with external ring under axial load are studied and discussed. After verification of the present numerical model with the results of several available experimental tests, 156 FE models were generated and analyzed to parametrically evaluate the effect of the joint geometry and the ring geometry on the SCFs. Results indicated that the SCF of the stiffened T-joints at crown point can be down to 24% of the SCF of the corresponding un-reinforced joint at the same point. Also, the effect of the ring on the SCF at saddle point is more remarkable than the effect of the ring on the SCF at crown point. Moreover, against un-reinforced joints under axial load, the SCF at saddle point of the stiffened joint is smaller than the SCF at crown point of that stiffened joint. The ring results in the redistribution of stresses in the ring and metal substrate. Also, the effect of the ring thickness on the decrease of the SCFs is slight and can be ignored. In final step, the geometric parameters affecting the SCFs of the stiffened T-joints are analyzed by multiple nonlinear regression analyses. An accurate formula is proposed for determining the SCFs.

• Korean Journal of Plant Resources
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• v.36 no.6
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• pp.562-570
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• 2023

The droplet-vitrification technique for cryopreservation has proven successful across a diverse range of germplasm, ensuring safe and effective long term preservation. In this study, we investigate an effective cryopreservation protocol using the droplet-vitrification technique for shoot tips of Freesia hybrida cultivars 'Sunny Gold' and 'Sweet Lemon'. To determine optimal conditions for Freesia cryopreservation, we employed a carefully selected standard procedure along with additional treatments and alternative solutions. For 'Sunny Gold', the highest regrowth rate of 24% was achieved when shoot tips underwent dehydration with PVS3 solution for 120 minutes before direct immersion in liquid nitrogen (LN) for 1 hour, coupled with a standard protocol involving a two-step preculture with 0.3 M - 0.5 M sucrose, loading with C4 for 40 minutes, and unloading with 0.8 M sucrose for 40 minutes. In the case of 'Sweet Lemon,' regrowth of cryopreserved shoot tips was observed with dehydration treatments, including PVS2 (A3) for 60 minutes and PVS3 (B1) for 60 minutes, as well as longer exposure. The results reflect the distinct sensitivity of shoot tips to chemical toxicity and osmotic stress in these two genotypes. This study provides valuable evidence to consistently enhance the effectiveness of cryopreservation methods for the long-term conservation of Freesia germplasm.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.306-313
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• 2023

Having pet is one of the activities people living in modern society do to relieve stress and find peace of mind. Currently, the object of companion animals has moved beyond being a real 'living entity' and has developed to a stage where the animal's upbringing process can be enjoyed in a virtual space by being programmed in digital content. This paper studies detailed elements such as character design, interaction, and realism of 'Tamagotchi (1996)', which can be said to be the beginning of digital training content, and 'Peridot (2023)', a recently introduced augmented reality-based training content. The point was that it was training content using portable electronic devices. However, while the environment in the electronic device in which Tamagotchi's character exists was a simple black and white screen, the environment in which Peridot's character operates has been changed to the real world projected on the screen based on augmented reality. Mutual communication with characters in Tamagotchi remained a response to pressing buttons, but in Peridot, it has advanced to the point where you can pet the characters by touching the smartphone screen. In addition, through object and step recognition, it was confirmed that the sense of reality had become more realistic, with toys thrown by users on the screen bouncing off real objects. We hope that this research material will serve as a useful reference for the development of digital training content to be developed in the near future.

• Tribology and Lubricants
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• v.39 no.6
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• pp.244-249
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• 2023

This paper presents a comprehensive analysis of the impact of surface roughness on the friction and wear properties of SUS 321, an austenitic stainless steel variant produced using the laser powder bed fusion (LPBF) technique, which is a prevalent additive manufacturing method. After the LPBF fabrication, the specimens go a heat treatment process aimed at alleviating residual stress. Subsequently, they are polished extensively to achieve a refined and smooth surface. To deliberately introduce controlled variations in surface roughness, an etching process is employed. This multi-step method encompassed primary etching in a 3M hydrochloric acid solution, followed by secondary etching in a 35 wt% ferric chloride solution, with varying durations applied to different specimens. A comprehensive evaluation of the surface characteristics ensued, employing precise techniques such as surface roughness measurements and meticulous assessments of water droplet contact angles. Following the surface treatment procedures, a series of friction tests are performed to explore the tribological behavior of the etched specimens. This in-depth investigation reached its peak by revealing valuable insights. It clarified a strong correlation between intentionally altered surface roughness, achieved through etching processes, and the resulting tribological performance of LPBF-fabricated SUS 321 stainless steel. This significantly advances our grasp of material behavior in tribological applications.

• Molecules and Cells
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• v.46 no.11
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• pp.655-663
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• 2023

Autophagy dysfunction is associated with human diseases and conditions including neurodegenerative diseases, metabolic issues, and chronic infections. Additionally, the decline in autophagic activity contributes to tissue and organ dysfunction and aging-related diseases. Several factors, such as down-regulation of autophagy components and activators, oxidative damage, microinflammation, and impaired autophagy flux, are linked to autophagy decline. An autophagy flux impairment (AFI) has been implicated in neurological disorders and in certain other pathological conditions. Here, to enhance our understanding of AFI, we conducted a comprehensive literature review of findings derived from two well-studied cellular stress models: glucose deprivation and replicative senescence. Glucose deprivation is a condition in which cells heavily rely on oxidative phosphorylation for ATP generation. Autophagy is activated, but its flux is hindered at the autolysis step, primarily due to an impairment of lysosomal acidity. Cells undergoing replicative senescence also experience AFI, which is also known to be caused by lysosomal acidity failure. Both glucose deprivation and replicative senescence elevate levels of reactive oxygen species (ROS), affecting lysosomal acidification. Mitochondrial alterations play a crucial role in elevating ROS generation and reducing lysosomal acidity, highlighting their association with autophagy dysfunction and disease conditions. This paper delves into the underlying molecular and cellular pathways of AFI in glucose-deprived cells, providing insights into potential strategies for managing AFI that is driven by lysosomal acidity failure. Furthermore, the investigation on the roles of mitochondrial dysfunction sheds light on the potential effectiveness of modulating mitochondrial function to overcome AFI, offering new possibilities for therapeutic interventions.

• Geomechanics and Engineering
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• v.20 no.6
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• pp.537-546
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• 2020

Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.

• The korean journal of orthodontics
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• v.38 no.1
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• pp.13-30
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• 2008

Objective: The objective of this study was to evaluate the displacement pattern and the stress distribution of the finite element model 3-D visualization during symphyseal widening according to the osteotomy position, osteotomy type, and distraction device. Methods: The kinds of distraction devices used were tooth-borne type, hybrid type, bone-borne type and tooth-borne type $30^{\circ}$ angulated, and the kinds of osteotomy design were vertical osteotomy line between the central incisors and step osteotomy line through the symphysis. Results: All reference points of the mandible including the condyles were displaced laterally irrespective of the osteotomy position, osteotomy method and distraction device. The anteroposterior or vertical displacements showed small differences between the groups. The widening pattern of the osteotomy line in the tooth-borne type of device was v shaped, and that of bone-borne type was a reverse v shape. However, the pattern in the hybrid type was parallel. The lateral displacement of the mandibular angle by the bone-borne device was more remarkable than the other types of devices. The displacement by the $30^{\circ}$ angulated tooth-borne type was different between the left and right sides in both the transverse and anteroposterior aspects. Conclusion: The design of the distraction devices and osteotomy line can influence the displacement pattern and the stress distribution during mandibular symphyseal distraction osteogenesis procedures.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.

• Journal of the Korean Geotechnical Society
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• v.24 no.2
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• pp.67-75
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• 2008

It is interesting to note that distinct element method has been used extensively to model the response of micro and discontinuous behavior in geomechanics. Impressive advances related to response of distinct particles have been conducted and there were difficulties in considering fluid effect simultaneously. Current distinct element methods are progressively developed to solve particle-fluid coupling focused on fluid flow through soil, rock or porous medium. In this research, numerical simulations of fluid injection into particulate materials were conducted to observe cavity initiation and propagation using distinct element method. After generation of initial particles and wall elements, confining stress was applied by servo-control method. The fluid scheme solves the continuity and Navior-Stokes equations numerically, then derives pressure and velocity vectors for fixed grid by considering the existence of particles within the fluid cell. Fluid was injected as 7-step into the assembly in the x-direction from the inlet located at the center of the left boundary under confining stress condition, $0.1MP{\alpha}\;and\;0.5MP{\alpha}$, respectively. For each simulation, movement of particles, flow rate, fluid velocity, pressure history, wall stress including cavity initiation and propagation by interaction of flulid-paricles were analyzed.

• Korean Journal of Culture and Social Issue
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• v.29 no.1
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• pp.75-99
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• 2023

The current study aimed to explore the suicidal behaviors and risk factors of completed suicides using psychological autopsy and use them as index variables to classify suicidal types. In addition, this study looked into the influential factors that affect each suicidal type. related to suicidal behaviors and suicidal risk factors by psychological autopsy. In addiction, the distinctions among the classes were analyzed. For this, psychological autopsies were conducted on the families and the close ones of 128 completed suicides. Then, the index variables were finally chosen for classifying suicidal types. The selected index variables for suicidal risk factors were mental disorders, suicide/self-harm, significant changes in physical appearance, marital conflict, adjustment and relationship issues at work/school, unemployment/layoff, jobless status and serious financial problems. The selected index variables for suicidal behaviors were expressing their suicidal attempts, writing suicidal notes, asking for help, the time/place/method of suicidal behavior, past suicidal/self-harm experience and the first person who witnessed the suicide. The Latent Class Analysis(LCA) and the 3-step method were used for classifying suicidal types. Then external variables(financial changes, cohabitation, existence of stressors, changes in stress level or relationships and family members with mental disorder/alchohol problems/ physical disorders, and work/school stisfaction) were applied for distinguishing classes. As a result, 5 classes(financial problems, adjustment problems, complex problems, psychiatric problems, and response to event[s]) were revealed on suicidal behaviors and 3 classes(residence- suicidal attempt- found by family, nonresidence- nonsuicidal attempt- found by acquaintances, residence- nonsuicidal attempt- found by family) were presented on suicidal risk factors. External variables such as gender, marital status, cohabitation, changes in relationships significantly differentiated among the 3 classes. Especially, class 3(residence- nonsuicidal attempt- found by family) tended to cohabit with others, were married, and had a significantly high level of interpersonal conflicts. When comparing the 5 classes of suicidal risk factors, auxiliary variables such as economic changes, cohabitation, stress, relationship changes, and family-related problems, and school/work satisfaction significantly differentiated the 5 classes. Especially class 3 (complex problems) experienced comparatively less family-related problems, but showed an aggravating level of personal stress. Suicial prevention strategies should be provided considering the characteristics of each class and the influential factors.