• PNF and Movement
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• v.15 no.1
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• pp.1-11
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• 2017

Purpose: The purpose of this study was to use an ICF tool in an intervention for anterior cruciate ligament reconstruction (ACLR) patients to examine and evaluate the patients' functional problems, measure the results of the intervention, and present the process of preparing proprioceptive neuromuscular facilitation (PNF) intervention strategies, thereby contributing to changes in and development of relevant future clinical practices. Methods: A PNF rehabilitation exercise program using an ICF tool was applied to ACLR patients five times per week for four weeks. To measure the resulting changes, the ICF evaluation display, the visual analog scale (VAS), the manual muscle test (MMT), the range of motion (ROM) test, the Lysholm knee score (LKS), and the muscle endurance test (MET) were used. Results: After the intervention was applied to the ACLR patients, improvements were achieved in all the tests: ICF evaluation display, VAS, MMT, ROM, LKS, and MET. Conclusion: Utilizing the ICF tool, this study identified functional problems of ACLR patients. When the intervention was applied, physical functions improved, and structural damage was reduced, leading to enhanced levels of functional activities such as postural changes, posture maintenance, gait, movements, and movements between different places. The patients were able to complete the teacher training, which was their goal.

• Smart Structures and Systems
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• v.19 no.1
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• pp.1-10
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• 2017

The operation of subway trains induces secondary structure-borne vibrations in the nearby underground spaces. The vibration, along with the associated noise, can cause annoyance and adverse physical, physiological, and psychological effects on humans in dense urban environments. Traditional tethered instruments restrict the rapid measurement and assessment on such vibration effect. This paper presents a novel approach for Wireless Smart Sensor (WSS)-based autonomous evaluation system for the subway train-induced vibrations. The system was implemented on a MEMSIC's Imote2 platform, using a SHM-H high-sensitivity accelerometer board stacked on top. A new embedded application VibrationLevelCalculation, which determines the International Organization for Standardization defined weighted acceleration level, was added into the Illinois Structural Health Monitoring Project Service Toolsuite. The system was verified in a large underground space, where a nearby subway station is a good source of ground excitation caused by the running subway trains. Using an on-board processor, each sensor calculated the distribution of vibration levels within the testing zone, and sent the distribution of vibration level by radio to display it on the central server. Also, the raw time-histories and frequency spectrum were retrieved from the WSS leaf nodes. Subsequently, spectral vibration levels in the one-third octave band, characterizing the vibrating influence of different frequency components on human bodies, was also calculated from each sensor node. Experimental validation demonstrates that the proposed system is efficient for autonomously evaluating the subway train-induced ambient vibration of underground spaces, and the system holds the potential of greatly reducing the laboring of dynamic field testing.

• Journal of Hydrogen and New Energy
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• v.32 no.5
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• pp.315-323
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• 2021

The air-cooled proton exchange membrane fuel cells (PEMFC) stacks, which is widely used in small-sized PEMFC, have a problem in that durability is weaker than that of the water-cooled type. Because the cathode is open to the atmosphere and the structural problem of the air-cooled stack, which is difficult to maintain airtightness, is highly likely to form a hydrogen/air boundary during start-up/shut-down (SU/SD). Through the accelerated durability evaluation of the 20 W air-cooled PEMFC stack, the purpose of this study was to find out the cause of the degradation of the stack and to contribute to the improvement of the durability of the air-cooled PEMFC stack. In this study, it was possible to evaluate durability in a relatively short time by reducing 20-30% of initial performance by repeating SU/SD 1,000 to 1,200 times on an air-cooled PEMFC stack. After disassembling the stack, each cell was divided into two and the performance analysis showed that the electrode degradation was more severe in the anode outlet membrane electrode assembly (MEA), which facilitates air inflow as a whole, than in the inlet MEA. It was shown that the cathode Pt was dissolved/precipitated to deteriorate the polymer ionomer inside the membrane.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2982-2989
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• 2021

One of the consequences of the 475 ℃ embrittlement of duplex stainless steels is the reduction of the resistance to localized corrosion. Therefore, the detection of this type of embrittlement before the material exhibits significant loss in toughness, and corrosion resistance is important to ensure the structural integrity of critical components under corrosion threats. In this research, conductivity measurements are performed using the alternating current potential drop (ACPD) technique with using a portable four-point probe as a nondestructive evaluation (NDE) method for detecting the embrittlement in a 2507 (UNS S32750) super duplex stainless steel (SDSS) aged at 475 ℃ from as-received condition to 300 h. The electric conductivity results were compared against two electrochemical tests namely double loop electrochemical potentiokinetic reactivation (DL-EPR) and critical pitting temperature (CPT). Mechanical tests and the microstructure characterized using scanning electron microscopy (SEM) imaging are conducted to track the progress of embrittlement. It is shown that the electric conductivity correlates with the changes in impact energy, microhardness, and CPT corrosion tests result demonstrating the feasibility of the four-point probe as a possible field-deployable method for evaluating the 475 ℃ embrittlement of 2507 SDSS.

• Journal of Neurogastroenterology and Motility
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• v.24 no.4
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• pp.584-592
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• 2018

Background/Aims There is uncertainty about how to measure outcomes reported by patients in gastroesophageal reflux disease (GERD). This study was conducted to develop an instrument and to determine of the definition of respondent for a patient reported outcomes to assess the efficacy of a treatment used for GERD treatment. Methods A structural process has developed a self-evaluation questionnaire for GERD (SEQ-GERD); health-related quality of life questionnaire for GERD (GERD-QOL) was translated through cross-cultural validation. Two-week reproducibility was evaluated and construct validity was assessed by correlating the SEQ-GERD with the Patient Assessment of Gastrointestinal Disorders (PAGI-SYM), the reflux disease questionnaire (RDQ), and GERD-QOL. Changes in SEQ-GERD scores were compared to assess the discriminative validity following 4 weeks of proton pump inhibitor administration. Results A total of 83 Korean patients were included (mean age $46{\pm}14$ years, females 61.4%). The internal consistency of the 19-item SEQ-GERD was good (alpha = 0.60-0.94) and the test-retest reliability was high (intra-class correlation coefficient = 0.67-0.95). The SEQ-GERD highly correlated with the GERD domain of the PAGI-SYM (correlation coefficient r = 0.894, P < 0.001), the RDQ-GERD (r = 0.877, P < 0.001), and GERD-QOL (r = -0.536, P < 0.05). SEQ-GERD scores significantly varied according to the overall treatment effectiveness scale of drug responsiveness and significantly decreased after drug treatment (mean differences according to the overall treatment effectiveness scale, P = 0.020). Conclusion This study supports that SEQ-GERD is reliable and valid, and can be used to evaluate the treatment response in patients with GERD.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.2
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• pp.75-81
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• 2019

In this study 24 power transmission towers were selected by considering various variables such as power transmission capacity, height and structural type to evaluate their seismic performance using the standard design response spectrum recently announced by the government. In addition, the stresses and sectional forces generated by the current design wind loads and revised seismic ones were compared to review the effects on the design of power transmission towers when the government-required seismic standards were raised. The results of seismic performance evaluation for the target power transmission towers showed that they had seismic capacity of 0.31~0.91g, and that they met the level of the earthquake-resistant special grade, which is the 2,400-year earthquake return periods and secured seismic safety. Further, the sectional forces caused by earthquakes in the towers were 33~82.5% of the ones due to wind loads, and it was also confirmed that the design wind loads were more dominant than design earthquake ones under the elevated seismic standards.

• Earthquakes and Structures
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• v.16 no.3
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• pp.265-277
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• 2019

Framed masonry wall structures represent a typical high-rise structural system that are also seismically vulnerable. During ground motions, they are excited in both in-plane and out-of-plane terms. The interaction between the frame and the infill during ground motion is a highly investigated phenomenon in the field of seismic engineering. This paper presents a numerical investigation of two distinct static out-of-plane loading methods for framed masonry wall models. The first and most common method is uniformly loaded infill. The load is generally induced by the airbag. The other method is similar to in-plane push-over method, involves loading of the frame directly, not the infill. Consequently, different openings with the same areas and various placements were examined. The numerical model is based on calibrated in-plane bare frame models and on calibrated wall models subjected to OoP bending. Both methods produced widely divergent results in terms of load bearing capabilities, failure modes, damage states etc. Summarily, uniform load on the panel causes more damage to the infill than to the frame; openings do influence structures behavior; three hinged arching action is developed; and greater resistance and deformations are obtained in comparison to the frame loading method. Loading the frame causes the infill to bear significantly greater damage than the infill; infill and openings only influence the behavior after reaching the peak load; infill does not influence initial stiffness; models with opening fail at same inter-storey drift ratio as the bare frame model.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.5
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• pp.269-277
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• 2019

In a seismic design, a structural demand by an earthquake load is determined by design response spectra. The ground motion is a three-dimensional movement; therefore, the design response spectra in each direction need to be assigned. However, in most design codes, an identical design response spectrum is used in two horizontal directions. Unlike these design criteria, a realistic seismic input motion should be applied for a seismic evaluation of structures. In this study, the definition of horizontal spectral acceleration representing the two-horizontal spectral acceleration is reviewed. Based on these methodologies, the horizontal responses of observed ground motions are calculated. The data used in the analysis are recorded accelerograms at the stations near the epicenters of recent earthquakes which are the 2007 Odeasan earthquake, 2016 Gyeongju earthquake, and 2017 Pohang earthquake. Geometric mean-based horizontal response spectra and maximum directional response spectrum are evaluated and their differences are compared over the period range. Statistical representation of the relations between geometric mean and maximum directional spectral acceleration for horizontal direction and spectral acceleration for vertical direction are also evaluated. Finally, discussions and suggestions to consider these different two horizontal directional spectral accelerations in the seismic performance evaluation are presented.

• Journal of Broadcast Engineering
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• v.24 no.3
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• pp.515-526
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• 2019

In the real world, the user's preference for a particular product is determined by many factors besides the quality of the product. The reflection of these external factors was very difficult because of various fundamental problems including lack of data. However, access to external factors has become easier as the infrastructure for public data is opened and the availability of evaluation platforms with diverse and vast amounts of data. In accordance with these changes, this paper proposes a recommendation system structure that can reflect the collectable factors that affect user's preference, and we try to observe the influence of actual influencing factors on preference by applying case. The structure of the proposed system can be divided into a process of selecting and extracting influencing factors, a process of supplementing insufficient data using sentence analysis, and finally a process of combining and merging user's evaluation data and influencing factors. We also propose a validation process that can determine the appropriateness of the setting of the structural variables such as the selection of the influence factors through comparison between the result group of the proposed system and the actual user preference group.

• The Mathematical Education
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• v.58 no.1
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• pp.41-54
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• 2019

The purpose of this study was to examine the effects of career identity on learning persistence and academic achievement, and mediating effect of utility value. To examine the effect of mediating role of utility value, we divided utility value into two types, utility value of daily matters and utility value of career. This study was conducted on 228 senior students in high school, to investigate relations among career identity, utility value, learning persistence and academic achievement in mathematics, by using the structural equation model. The results are as follows. First, career identity positively predicted learning persistence in mathematics. Second, career identity positively predicted the utility value of daily matters and career. Third, both type of utility value in mathematics positively predicted learning persistence in mathematics. Fourth, the utility value of daily matters and career, in mathematics subjects, showed differential predictability toward learning persistence and academic achievement. Both type of utility value in mathematics positively predicted learning persistence, but showed differential predictability toward learning academic achievement. Specifically, the utility value of daily matters in the near future did not predict the academic achievement, but the utility value of career in the distant future positively predicted the academic achievement. Fifth, the utility value was found to play a mediating role in the relationship between career identity and learning persistence. Based on the results of this study, implications for mathematics education were discussed.