• Resources Recycling
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• v.32 no.2
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• pp.33-42
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• 2023

Metal emulsions have been studied for several decades as a method of increasing the efficiency of the steelmaking process. This study was performed using a water model, observable at room temperature, to compensate for the disadvantages of the high-temperature experiment, the results of which are difficult to observe visually. As a substitute for metal-in-slag emulsions, experiments were conducted by dropping distilled water into silicone oil and comparing the results with the results of a calculation by momentum balance equations. The descending velocity of the water droplet decreased as the diameter of the droplet and viscosity of the fluid (silicon oil) increased. To simulate the descending velocity of a water droplet in silicon oil under stirring conditions, the flow rate of the fluid (silicon oil) was measured by particle image velocimetry (PIV) methods. The calculation of the descending velocity of the water droplet was in good agreement with the measured values, with and without stirring a viscous silicone oil.

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.400-408
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• 2023

Objective : Nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2) is a crucial factor for the survival of neuron. The role of NMNAT2 in damage following traumatic brain injury (TBI) remains unknown. This study was designed to investigate the role of NMNAT2 in TBI-induced neuronal degeneration and neurological deficits in rats. Methods : The TBI model was established in Sprague-Dawley rats by a weight-dropping method. Real-time polymerase chain reaction, western blot, immunofluorescence, Fluoro-Jade C staining, and neurological score analyses were carried out. Results : NMNAT2 mRNA and protein levels were increased in the injured-side cortex at 6 hours and peaked 12 hours after TBI. Knocking down NMNAT2 with an injection of small interfering RNA in lateral ventricle significantly exacerbated neuronal degeneration and neurological deficits after TBI, which were accompanied by increased expression of BCL-2-associated X protein (Bax). Conclusion : NMNAT2 expression is increased and NMNAT2 exhibits neuroprotective activity in the early stages after TBI, and Bax signaling pathway may be involved in the process. Thus, NMNAT2 is likely to be an important target to prevent secondary damage following TBI.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.153-153
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• 2021

Storm Storm event is one of major issues in South Korea due to devastating damage at its landfall. A series of statistical study on the historical typhoon records consistently insist that the typhoon translation speed (TS) is on slowdown trend annually, and thus provides an urgent topic in assessing the extreme storm surge under future climate change. Even though TS has been regarded as a principal contributor in storm surge dynamics, only a few studies have considered its impact on the storm surge. The landfall angle (LA), another key physical factor of storm surge also needs to be further investigated along with TS. This study aims to elucidate the interaction mechanism among TS, LA, coastal geometry, and storm surge synthetically by performing a series of simulations on the idealized geometries using Delft3D FM. In the simulation, various typhoons are set up according to different combinations of TS and LA, while their trajectories are assumed to be straight with the constant wind speed and the central pressure. Then, typhoons are subjected to make landfall over a set of idealized geometries that have different depth profiles and layouts (i.e., open coasts or bays). The simulation results show that: (i) For the open coasts, the maximum surge height (MSH) increases with increasing TS. (ii) For the constant bed level, a typhoon normal to the coastline resulted in peak MSH due to the lowest effect of the coastal wave. (iii) For the continental shelf with different widths, the slow-moving typhoon will generate the peak MSH around a small LA as the shelf width becomes narrow. (iv) For the bay, MSH enlarges with the ratio of L/E (the length of main-bay axis /gate size) dropping, while the greatest MSH is at L/E=1. These findings suggest that a fast-moving typhoon perpendicular to the coastline over a broad continental shelf will likely generate the extreme storm surge hazard in the future, as well as the slow-moving typhoon will make an acute landfall over a narrow continental shelf.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.86-93
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• 2023

Pyrotechnic separation devices have been widely used as holding and release mechanism for deployable appendage. However, pyro-shock can cause temporal or permanent damage on shock sensitive components such as electronics, mechanism, and brittle components. This study proposed a low-stiffness blade based passive shock absorber using a multi-layered stiffener laminated with viscoelastic acrylic tapes for reducing transmitted pyro-shock upon explosion of pyrotechnic separation devices. The multi-layered structure with viscoelastic tape has high-damping characteristics to effectively secure structural integrity of low-stiffness blades under the launch environment. The design effectiveness was verified through a shock test by dropping a pendulum. The structural integrity of the shock absorber under a launch environment was evaluated through structural analysis under load conditions with a deployable payload.

• The Research Journal of the Costume Culture
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• v.31 no.3
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• pp.277-295
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• 2023

The Body Appreciation Scale-2 (BAS-2) measures the extent to which individuals feel, accept, and respond to their own bodies in a positive manner. Given the research need to explore positive body image and its associations with various sociocultural factors and related consequences among individuals with various cultural backgrounds, several studies have established the psychometric properties and factor structures of the BAS-2 in different languages and samples with different characteristics. The current study investigated the psychometric properties and measurement invariance of a Korean version of the BAS-2 in an older Korean adult population (599 older Korean adults with the average age of 70 years). Data were collected using both online and offline (paper-based) survey questionnaires. The results of exploratory factor analyses and confirmatory factor analysis evidenced the unidimensional factor structure and measurement invariance of the Korean BAS-2 among older Korean men and women, after dropping item 1. Scalar invariance was supported across gender, and men and women did not significantly differ in observed mean scores of the Korean BAS-2. The results also supported good convergent validity and criterion validity. Incremental validity was demonstrated by predicting self-esteem over and above measures of age, BMI, subjective financial and health status, body esteem, and ageism. High internal reliability and test-retest reliability over a 2-week period were confirmed. Overall, the results of this study support the reliable use of a Korean BAS-2 to measure positive body image among older Koreans after excluding item 1.

• Geomechanics and Engineering
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• v.34 no.2
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• pp.209-220
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• 2023

In this study, a series of three-dimensional numerical analyses were carried out to investigate the penetration performance of a dynamically installed Hall anchor. The advanced coupled Eulerian-Lagrangian (CEL) technique was adopted to accurately simulate the large soil deformation during the vertical penetration of a Hall anchor. In total, 52 numerical analyses were conducted to investigate the relationship between anchor penetration depth and the initial kinematic energy. Moreover, a sensitivity analysis was performed to investigate the effects of soil shear strength and soil type on the penetration mechanism of a drop anchor under self-weight. There is a monotonic increase in the penetration depth with an increasing anchor weight when the topsoil of the riverbed is not subjected to erosion. On the other hand, all the computed depths significantly increase when soil erosion is taken into consideration. This is mainly due to an enhanced initial kinematic energy from an increased dropping depth. Both depths increase exponentially with the initial kinematic energy. An enhanced shear strength can potentially increase the side resistance and end-bearing pressure around a drop anchor, thus significantly reducing the downward penetration of a hall anchor. Design charts are developed to directly estimate penetration depth and associated plastic zone due to dynamically installed anchor at arbitrary soil shear strength and anchor kinematic energy.

• Journal of Sensor Science and Technology
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• v.33 no.1
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• pp.24-29
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• 2024

Inkjet printing technology is used to mass-produce displays and electrochemical sensors by dropping tens of pico-liters or less of specific-purpose ink through nozzles, just as ink is sprayed and printed on paper. Unlike the deposition method for vaporizing material in a vacuum, inkjet printing technology can be used for processing even under general atmospheric pressure and has a cost advantage because the material is dissolved in a solvent and used in the form of ink. In addition, because it can only be printed on the desired part, masks are not required. However, a technical shortcoming is the difficulty for commercialization, such as uniformity for forming the thickness and coffee ring effect. As sizes of devices decrease, the need to print electrodes with precision, thinness, and uniformity increases. In this study, we improved the printing and processing conditions to form a homogeneous electrode using Ag ink (DGP-45LT-15C) and applied this for patterning to fabricate a heat sensor. Upon the application of voltage to the heat sensor, the model with an extended width exhibited superior heat performance. However, in terms of sheet resistance, the model yielded an equivalent value of 21.6 Ω/□ compared to the ITO.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.5
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• pp.1390-1411
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• 2024

Underwater Wireless Sensors Networks (UWSNs) are deployed in remotely monitored environment such as water level monitoring, ocean current identification, oil detection, habitat monitoring and numerous military applications. Providing scalable and efficient routing is very challenging in UWSNs due to the harsh underwater environment. The biggest difficulties are the nodes inherent movement due to water current, long delay in data transmission, low bandwidth of the acoustic signal, high error rate and energy scarcity in battery powered nodes. Many routing protocols have been proposed to solve the aforementioned problems. There are three broad categories of routing protocols namely depth based, energy based and vector-based routing. Vector Based Forwarding protocols perform routing through virtual pipeline by defining their radius which give proper direction to packets communication. We proposed a routing protocol termed as Path-Oriented Energy Scaled Expanded Vector Based Forwarding (PESEVBF). PESEVBF takes into account all parameters; holding time, the source nodes packets routing path and void holes creation on the second hop; PESEVBF not only considers the packet upward advancement but also focus on density of the forwarded nodes in terms of number of potential forwarding and suppressed nodes for path selection. Node selection in resultant holding time is based on minimum Path Factor (PF) value. Moreover, the suppressed node will be selected for packet forwarding to avoid the void holes occurrences on the second hop. Performance of PESEVBF is compared with other routing protocols using matrices such as energy consumption, packet delivery ratio, packets dropping ratio and duplicate packets creation indicating considerable performance improvement.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.123-131
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• 2024

The dispute between SK and Netflix, which has been going on for more than three years, ended in the direction of dropping the lawsuit and establishing a cooperative relationship between the two companies. However, as Internet traffic usage is likely to increase further in the future due to digital transformation and activation of generated AI, conflicts between domestic mobile carriers and global CP operators over network usage fees can arise at any time. In this study, the issues of the dispute related to network usage fees that occurred between SK and Netflix were examined, and different implications were drawn for each issue. The cost and scope of network usage considerations are an issue that must be determined entirely by negotiations between operators. However, if a dispute occurs between operators, user damage such as speed delays may occur, so it is necessary to prepare a policy alternative. As the domestic media industry has grown cooperatively with global CPs, it is considered important to form a reciprocal relationship between domestic mobile telecommunication operators and global CP operators regarding network usage fees in the future.

• Imaging Science in Dentistry
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• v.54 no.3
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• pp.251-256
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• 2024

Purpose: This study was performed to investigate the pattern of condylar pressure distribution in the discs of a patient diagnosed with disc displacement without reduction. Materials and Methods: This research consisted of a pre- and post-test observational clinical study. A patient diagnosed with disc displacement without reduction underwent treatment with an occlusal splint for 3 months. Finite element analysis employed a 3-dimensional model constructed from magnetic resonance images of the patient, taken both before the application of the splint and 3 months after its use. Results: The post-test model demonstrated a decrease in condylar pressure on the disc, with measurements dropping to 72 MPa from the pre-test level of 143 MPa. In the pre-test, the pressure distribution pattern was concentrated on the lateral posterior border, whereas in the post-test, it shifted toward the intermediate zone of the disc. Conclusion: Utilization of a stabilization splint for 3 months resulted in decreased pressure and a marked change in the pressure distribution pattern on the temporomandibular disc.