• The Journal of Engineering Geology
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• v.31 no.4
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• pp.719-730
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• 2021

An improved packer and injection system was developed to improve the efficiency of excavation by hydraulic rock splitting by reducing vibration and noise. Field testing of the system found hydraulic fractures limited in expansion and extension due to the loss of injection pressure by leackage from the cracks, and then the single packer applied to injection hole allowed to produce a sufficient tensile displacement for rock excavation. Numerical analysis based on the field test data could explain the development of cracks in the field experiments.

• Journal of Korean Academy of Nursing
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• v.49 no.4
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• pp.486-494
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• 2019

Purpose: To investigate the effect of $Buzzy^{(R)}$ and $ShotBlocker^{(R)}$ on reducing pain induced by intramuscular penicillin injections in children. Methods: This was a randomized controlled study. A total of 150 Turkish children aged 7~12 years who presented to our pediatric emergency clinic and met the inclusion criteria were recruited. The children were randomly assigned to each group (control=50, $Buzzy^{(R)}=50$, $ShotBlocker^{(R)}=50$). Data were collected using an information form, the State-Trait Anxiety Inventory for Children, Visual Analog Scale, and Faces Pain Scale-Revised. Results: The children in the control group had significantly higher pain scores during the penicillin injection than the children in the $ShotBlocker^{(R)}$ and $Buzzy^{(R)}$ groups. The children in the $Buzzy^{(R)}$ group had significantly less pain than the children in both the $ShotBlocker^{(R)}$ and control groups (p<.001). Conclusion: $Buzzy^{(R)}$ was more effective compared with $ShotBlocker^{(R)}$ in this study.

• International Journal of High-Rise Buildings
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• v.8 no.2
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• pp.117-123
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• 2019

Tall buildings are prone to wind-induced vibrations due to their slenderness whereby peak structural accelerations may be higher than the recommended maximum value. The common countermeasure is the installation of a tuned mass damper (TMD) near the highest occupied floor. Due to the extremely large modal mass of tall buildings and because of the narrow to broad band type of wind excitation the TMD mass may become inacceptable large - in extreme cases up to 2000 metric tons. It is therefore a need to develop more efficient TMD concepts which provide the same damping to the building but with reduced mass. The adaptive TMD concept described in this paper represents a solution to this problem. Frequency and damping of the adaptive TMD are controlled in real-time by semi-active oil dampers according to the actual structural acceleration. The resulting enhanced TMD efficiency allows reducing its mass by up to 20% compared to the classical passive TMD. The adaptive TMD system is fully fail-safe thanks to a smart valve system of the semi-active oil dampers. In contrast to active TMD solutions the adaptive TMD is unconditionally stable and its power consumption on the order of 1 kW is negligible small as controllable oil dampers are semi-active devices. The adaptive TMD with reduced mass, stable behavior and lowest power consumption is therefore a preferable and cost saving damping tool for tall buildings.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.2
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• pp.127-132
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• 2022

The growth of e-commerce market requires more delivery packagings, which protect goods from the damage factors on the delivery. In this study, we have analyzed the distribution environment data (vibration and impact) measured in previous study and compared with global standards (ISTA, ASTM), so that we developed the testing method for Field-to-Lab simulation suitable to the domestic delivery. In order to verify the efficacy of this method, we took the Field-to-Lab tests for 3 packaged products (detergents set, glass tableware set, small furniture), which has been frequent breakages or damages on the actual delivery by e-commerce order, so that we could find out the test results were similar to those of the actual delivery occasions. In addition, we could perform redesign and improvement of the parcel delivery packagings for safe transportation by taking this Field-to-Lab test repeatedly. This test methods was finally proposed to be Korean industrial standard (KS), and is expected to be useful as a designing tool for the packaging optimization between protecting goods and reducing packaging waste.

• Earthquakes and Structures
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• v.24 no.1
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• pp.1-9
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• 2023

A model for calculating structure interacted mechanics is proposed. A structural interaction model and controller design based on tuned mass damping (TMD) was developed to control the induced vibration. A key point is to introduce a new analytical model to evaluate the properties of the TMD that recognizes the motion-dependent nonlinear response observed in the simulations. Aiming at the problem of increased current harmonics and low efficiency of permanent magnet synchronous motors for electric vehicles due to dead time effect, a dead time compensation method based on neural network filter and current polarity detection is proposed. Firstly, the DC components and the higher harmonic components of the motor currents are obtained by virtue of what the neural network filters and the extracted harmonic currents are adjusted to the required compensation voltages by virtue of what the neural network filters. Then, the extracted DC components are used for current polarity dead time compensation control to avert the false compensation when currents approach zero. The neural network filter method extracts the required compensation voltages from the speed component and the current polarity detection compensation method obtains the required compensation voltages by discriminating the current polarity. The combination of the two methods can more precisely compensate the dead time effect of the control system to improve the control performance. Furthermore, based on the relaxed method, the intelligent approach of stability criterion can be regulated appropriately and the artificial TMD was found to be effective in reducing cross-wind vibrations.

• Steel and Composite Structures
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• v.48 no.4
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• pp.475-483
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• 2023

In this paper, a new energy-efficient semi-active hybrid bulk damper is developed that is cost-effective for use in structural applications. In this work, the possibility of active and semi-active component configurations combined with suitable control algorithms, especially vibration control methods, is explored. The equations of motion for a container bridge equipped with an MDOF Mass Tuned Damper (M-TMD) system are established, and the combination of excitation, adhesion, and control effects are performed by a proprietary package and commercial custom submodel software. Systematic methods for the synthesis of structural components and active systems have been used in many applications because of the main interest in designing efficient devices and high-performance structural systems. A rational strategy can be established by properly controlling the master injection frequency parameter. Simulation results show that the multiscale model approach is achieved and meets accuracy with high computational efficiency. The M-TMD system can significantly improve the overall response of constrained structures by modestly reducing the critical stress amplitude of the frame. This design can be believed to build affordable, safe, environmentally friendly, resilient, sustainable infrastructure and transportation.

• Journal of Practical Agriculture & Fisheries Research
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• v.26 no.2
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• pp.25-30
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• 2024

This study was conducted to develop the hanging type circular-patterned system that at maximizing the spatial efficiency of strawberry cultivation to increase yields, while also reducing labor and improving energy efficiency. The system consists of a cultivation bed units, longitudinal moving device, bed lifting device, front and rear transfer devices, lateral transfer device, nutrient supply device, and control unit. Performance testing revealed that the operational motor for longitudinal movement should have a torque of at least 0.1Nm based on the design weight and traction force of the cultivation bed unit. The power consumption required to move one cycle was calculated to be approximately 149Wh when performing harvesting or maintenance tasks for all 10 cultivation beds. Vibration angles measured during bed movement showed that the lateral transfer resulted in a roll angle ranging from -0.62° to 0.68° and a pitch angle ranging from -3.79° to 5.26°. For longitudinal transfer, the roll angle ranged from -3.37° to 3.36°, and the pitch angle ranged from -0.45° to 0.49°.

• International Journal of Advanced Culture Technology
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• v.12 no.3
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• pp.325-335
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• 2024

Existing research on walking aids has primarily focused on functional improvements, often neglecting negative aspects such as physical injuries and psychological discomfort, which limits the elderly's active participation in outdoor activities. This study aims to analyze issues related to outdoor walking stemming from physical and psychological factors in the elderly and to propose design directions for walking aids that align with their preferences. In-depth interviews were conducted with 13 elderly individuals aged 65 and above who use rollators, from May 2024 to June 2024. The interviews were analyzed using a questionnaire based on psychological factors identified in previous studies and functional aspects, utilizing Universal Design principles. The five-stage design thinking model from d.school was employed for problem definition. Issues related to walking aids were identified and analyzed during the 'Empathize' and 'Define' stages. The findings highlight priorities such as maintaining proper posture, reducing vibration, improving ease of folding and speed control, and providing additional storage space without causing discomfort. The proposed design directions reflect the needs and aspirations derived from the actual experiences of elderly individuals. The study's findings are expected to contribute to the development of walking aids that enhance usability and confidence, thereby improving the quality of life for elderly individuals.

• Structural Engineering and Mechanics
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• v.92 no.3
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• pp.257-266
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• 2024

An Earthquake is a natural phenomenon that causes the destruction of structures. For many years, various methods have been proposed to control this phenomenon. In modern times, a new method called active and passive control has been developed. Isolator systems are among the methods to control the structure's response. Instead of increasing the strength and capacity of the structure, these systems react to earthquakes. In this paper, a nonlinear rhombus shaped spring combined with the pendulum column isolation system was introduced that caused the piers to be flexible. The behavior of this isolator with flexible bases has been investigated. The studied system mathematical equations were derived, solved with MATLAB software, and compared with ABAQUS results. Later on, the isolator system was investigated under different earthquakes, and FFT analysis was performed on the results. The results demonstrate that this mechanism is suitable as an isolator because it reduces earthquake effects. It was observed that in the flexible piers form, the period was increased. The flexible piers have an effective role - in the response of the system-by reducing the system's stiffness considerably. Among the different damping ratios, those with ratios greater than 10% showed better results.

• Nuclear Engineering and Technology
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• v.56 no.11
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• pp.4895-4904
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• 2024

The helical-coiled once-through steam generator (H-OTSG) has the advantages of compact structure and strong heat transfer ability, and is appropriate for lead-cooled fast reactor. The two-phase flow instability may cause mechanical vibration and thermal fatigue of heat transfer tube bundles, posing a serious threat to the safe operation of the H-OTSG. In this work, the secondary side of the H-OTSG characterized as multi-parallel channels is modeled by RELAP5/MOD3.4 code, and the oscillation behavior during start-up and the influence of structural and operating parameters on system stability are studied based on time-domain method. The results indicate that the pressure, flow rate, and temperature of the secondary fluid exhibit density wave oscillations at the heating section in a (n-2,2) pattern. In addition, increasing inlet throttling, reducing outlet throttling, controlling subcooling within an appropriate range and avoiding operation under low loads are all beneficial for improving the system stability of the helical-coiled once-through steam generator.