• PNF and Movement
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• v.22 no.2
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• pp.233-242
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• 2024

Purpose: The aim of this study was to investigate the effects of different types of unstable loads on core and lower limb muscle activity during squatting. Methods: Nineteen subjects (all females) with resistance experience but no unstable resistance experience participated in the study. Subjects performed squats under three load conditions, and core and lower limb muscle activity was measured during eccentric and concentric contractions. Results: During the eccentric contraction, core and hip flexor activity was significantly higher with the aqua bag than with the barbell or resistance band, and for the quadriceps, the resistance band was significantly higher than the barbell. During the concentric contraction phase, core and hamstring muscle activity was significantly higher with the aqua bag than with the barbell and elastic band (p < 0.05). Conclusion: Squats with an aqua bag increase core and biceps brachii activation and can be recommended as a training method to improve trunk stability.

• The Korean Journal of Quaternary Research
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• v.33 no.1_2
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• pp.49-58
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• 2021

In the Paleoclimate Modeling Intercomparison Project phase 4 (PMIP4), various experiments for quaternary climatic change are being carried out along with the Coupled Model Intercomparison Project phase 6 (CMIP6). With the CMIP6 preindustrial climate experiment (piControl), the equilibrium climate simulations of 6 ka Holocene experiment (midHolocene), 21 ka Last Glacial Maximum experiment (lgm), and 127 ka Last Interglacial experiment (lig127k) experiment, and transient climate simulations of 850-1849 Common Era Last Millennium experiment (past1000), 21-9 ka last deglaciation, and 140-127 ka penultimate deglaciation experiment have been carried out under PMIP4 protocols by several modeling groups. In this technical note, important physical parameters and boundary conditions of these Tier 1 experiments and a list of additional Tier 2 and 3 experiments are summarized.

• Journal of Korean Society on Water Environment
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• v.40 no.4
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• pp.168-178
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• 2024

Wastewater treatment plants are constantly exposed to influent wastewater that is constantly changing. This poses a major challenge to the operation of the plants. It is crucial to have a rapid and accurate measurement of the influent concentrations of wastewater in order to maintain and optimize treatment performance, as well as to develop energy-saving strategies. While laboratory measurements provide the highest accuracy in determining influent water quality, they are inevitably time-consuming procedures. In order to cope with the ongoing disturbances from wastewater influent, absorption-based optical measuring instruments have been developed. These instruments can detect the influent water quality in a short amount of time, improving their practicality and reliability. However, when these optical measuring instruments malfunction, the accuracy of the measured values decreases, leading to unreasonable operation of the treatment plant. This paper proposes a method for detecting anomalies in optical water quality measurement devices. The Harmony Search algorithm is used to validate the measured water quality values and detect abnormalities such as contamination or physical anomalies in the measurement apparatus. To assess the performance of the developed algorithm in detecting anomalies, validation was conducted by installing it in a field-scale wastewater treatment plant. The results consistently showed that the developed fault detection method for optical water quality measurements equipment provided acceptable results for normal, temporary abnormal, and long-term abnormal conditions.

• Resources Recycling
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• v.33 no.4
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• pp.22-28
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• 2024

Waste PCBs contain a large amount of valuable resources, including copper, and technology to recover them is constantly being developed. Generally, to recycle waste PCBs, a physical pretreatment process such as shredding and crushing is required. However, during this stage, the loss rate of metals is high and the sorting efficiency is low, indicating a need for a more efficient recycling pretreatment process. In this study, a high-temperature milling process, which simultaneously employs heat treatment and ball milling, was utilized to efficiently recover copper from waste PCBs. An experiment was conducted at 350 ℃ with milling time, milling speed, and the weight of the balls as variables. The results showed a copper recovery rate of over 90% under the conditions of a ball weight of 500 g, a milling speed of 70 RPM, and a milling time of 5 hours. The purity of the recovered copper was approximately 93%, and through post-processing after the high-temperature milling process, the feasibility of reusing the recovered copper as a high-purity material was confirmed.

• Journal of the International Relations & Interdisciplinary Education
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• v.3 no.2
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• pp.67-85
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• 2023

Various support is being provided at the Office of Education level to resolve educational deficits and side effects caused by the prolonged COVID-19 pandemic. Because comprehensive support for teachers' physical and mental recovery is as important as support for student recovery, this paper looked at the teacher recovery support projects and best practices of the Chungcheongbuk-do Office of Education. The Chungcheongbuk-do Office of Education operates the Teacher Healing Support Center, operation of itinerant temporary teachers to support short-term classes for elementary and middle school students, supports for the operation of 'Elementary Life Assistants, advancement of the 'School Work Immediate Support System', development and production of easy and easy work help materials for low-experience teachers, and school autonomy. We are improving educational conditions through various supports for teacher recovery, such as organizing and operating an operation support group. In particular, in addition to providing opportunities for recharge, such as psychological and emotional healing support and healing training, streamlining school work and supporting workload reduction, such as restructuring school work and improving work methods, is significant as a more fundamental measure for teacher recovery. there is.

• Korean Journal of Materials Research
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• v.34 no.10
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• pp.506-514
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• 2024

High-frequency soft magnetic Ni, Fe, and Co-based thin films have been developed, typically as nanocrystals and amorphous alloys. These Ni, Fe, and Co-based thin films exhibit remarkably good frequency dependence up to high frequencies of several tens of MHz. These properties arise from the moderate magnetic anisotropy and fairly high electrical resistivity that result from the microstructural characteristics of the nanocrystalline and amorphous states. In this paper, Al-Co/AlN-Co and Al-N/AlN-Co multilayer films were deposited using two-facing-target type sputtering (TFTS). Their microstructures, magnetic and electrical properties were studied with the expectation that inserting Al-Co or Al-N as an interlayer could effectively reduce the coercive force and produce films with relatively high resistivity. A new approach is presented for the fabrication of Al-Co (Al-N)/AlN-Co multilayer films, prepared with the TFTS system. The deposited films were isothermally annealed at different temperatures and investigated for microstructure, magnetic properties and resistivity. The TFTS method used in this experiment is suitable for fabricating Al-Co(Al-N)/AlN-Co multilayer films with different layer thickness ratio (LTR). The annealing conditions, thickness of the multilayer film, and LTR can control the physical properties as well as the microstructure of the manufactured film. Magnetization and resistance increased and coercivity decreased as LTR decreased. The thin film with LTR = 0.175 exhibited high resistivity values of 2,500 µΩ-cm, magnetization of 360 emu/cm³, and coercivity of 5 Oe. Results suggests that thin films with such good resistivity and magnetization would be useful as high-density recording materials.

• Korean Journal of Gerontological Social Welfare
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• v.73 no.2
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• pp.9-47
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• 2018

Health status and loneliness, respectively, are major factors influencing depression among older adults. Meanwhile, there is the possibility that health status indirectly affects depression via loneliness. With regard to this indirect effects, however, age-friendly environments can make differences by providing community resources which help to compensate weakness of declining physical function and limited social participation due to vulnerable health status. In this context, this study examined moderated mediation effects of age-friendly environments on the indirect path from subjective health status to depression through loneliness. 615 adults aged 50 years and over from nationally conducted '2017 age integration survey' are analyzed. As a result, the tendency that poor subjective health status indirectly increased depression with mediated by loneliness was aggravated in less age-friendly environments. Consequently, the efforts to improve environmental conditions of less age-friendly communities are required first for the purpose of preventing older adults' depression caused by poor health status and loneliness.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.923-931
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• 2022

An increasing global population requires a greater food supply, and accordingly there is demand for enhanced production of rice, as a major crop plant that covers half of the world's population. Rice production in arid area is extremely difficult due to poor soil fertility, salinity, deficit of irrigation water, and weather conditions. The aim of the present study was to determine whether various fertilization recipes could provide a countermeasure to allow rice production while also providing soil amendment such as soil pH adjustment. The study was conducted at an experimental field of the United Arab-Emirates (UAE) from January to April, 2022. Rice seedlings (cv. Asemi, alkaline-resistant) were transplanted in plastic containers, and different types of water and nutrient managements were employed as follows: water management (flooding and aerobic for NPKs treatment group) and nutrient management (NPKs, slow release fertilizers [SRFs] and SRFs + NPK-1 treatment groups with flooding). Water and nutrient management did not show any effect on soil pH adjustment. Rice growth was significantly enhanced in the flooding compared to the aerobic condition, whereas the effect of nutrient management clearly differed among the treatment groups, with SRFs + NPK-1 showing the best results followed by SRFs and NPKs. Most of the fertilization groups markedly accumulated soluble sugars in the shoots and grains of rice plants, but concomitantly a decrease in the roots. Overall, the level of starch showed a tendency of relatively slight perturbation by fertilization. Taken together, the results indicate that soil physical structure should be preferentially amended to find the key for suitable rice production.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.2974-2989
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• 2024

The one-dimensional Two-Fluid concept uses an area-average approach to simplify the time and phase-averaged Two-Fluid conservation equations, making it more suitable for addressing difficulties at an industrial scale. Nevertheless, the mathematical framework has inherent weaknesses due to the loss of details throughout the averaging procedures. This limitation makes the conventional model inappropriate for some flow regimes, where short-wavelength perturbations experience uncontrolled amplification, leading to solutions that need to be physically accurate. The critical factor in resolving this problem is the integration of closure relations. These relationships play a crucial function in reintroducing essential physical characteristics, thus correcting the loss that occurs during averaging and guaranteeing the stability of the model. To improve the accuracy of predictions, it is essential to assess the stability and grid dependence of one-dimensional formulations, which are particularly affected by closure relations and numerical schemes. The current research presented in the text focuses on improving the well-posedness of the TFM, specifically within the TRACE code, which is widely utilized for nuclear reactor safety assessments. Incorporating a bubble collision model in the momentum equations is demonstrated to enhance the TFM's resilience, especially in scenarios with high void fractions where conventional TFMs may face challenges. The analysis presents a linear stability analysis performed for the transient one-dimensional Two-Fluid Model of system code TRACE within the framework of vertically dispersed flows. The main emphasis is on evaluating the stability characteristics of the model while also acknowledging its susceptibility to closure relations and numerical techniques.

• Korean Journal of Applied Biomechanics
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• v.34 no.3
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• pp.115-124
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• 2024

Objective: Based on the uncontrolled manifold (UCM) framework, this study investigated the hierarchical organization of redundant motor elements in multi-digit prehension, focusing on moment production across two control hierarchies. Method: Twelve adult males participated in the current experiment where they grasped a customized handle to generate and maintain target moments under isometric conditions in both pronation and supination directions. The forces exerted by the digits, recorded via transducers on the handle, underwent UCM analysis. This analysis quantified the synergistic actions across the upper and lower control hierarchies for stabilizing moments and grip forces. Additionally, synergy properties for lateral and medial fingers were analyzed to assess their distinct contributions (finger specialization) to moment and force stabilization. Results: Our findings revealed that the thumb and virtual finger contribute differently to net moment generation according to the direction of the moment, reflecting the different abilities of the individual fingers to produce moments. In the upper hierarchy, synergistic actions were notably stronger, effectively stabilizing both moments and grip forces. In contrast, the lower control hierarchy demonstrated a lack of synergy in force stabilization (trade-off synergy), although synergy in moment stabilization was preserved. Further, lateral fingers were found to play a more significant role in stabilizing moments compared to medial fingers. Conclusion: The pronounced synergy in grip force observed in the upper hierarchy implies that grip stabilization is likely an intrinsic strategy of the central nervous system, rather than merely a mechanical consequence. Furthermore, synergistic covariations of digit moments in both hierarchies indicate the neural controller's capability to generate synergies across hierarchies for stable multi-digit moment production. The notable contribution of lateral fingers in moment stabilization provides supporting evidence of finger specialization. Overall, this study elucidates the hierarchical interplay of redundant elements to achieve task-specific stability, especially in multi-digit prehension.